Final answer:
The G protein is involved with the elongation factor that brings aminoacyl-tRNAs to the A site of the ribosome during protein synthesis. The E. coli ribosome synthesizes proteins with remarkable speed, potentially translating a 200-amino acid protein in just 10 seconds, powered by GTP hydrolysis.
Step-by-step explanation:
The G protein mentioned in the question appears to refer to a specific elongation factor involved in the process of protein synthesis within the ribosome. During the elongation phase of translation, the ribosome moves along the mRNA, and with the help of GTP for energy, aminoacyl-tRNAs are brought into the A site of the ribosome. The E. coli translation apparatus is highly efficient, requiring only about 0.05 seconds to add each amino acid to a growing polypeptide chain, which enables the synthesis of a 200-amino acid protein in roughly 10 seconds.
Protein synthesis begins when an initiation complex forms, which includes the small ribosomal subunit, mRNA template, initiation factors, and a special initiator tRNA. The elongation phase involves the large ribosomal subunit and the sequential entry and exit of tRNAs at the A, P, and E sites. Notably, the energy for peptide bond formation and ribosomal translocation comes from the hydrolysis of GTP, catalyzed by separate elongation factors.
During each step of elongation, a new aminoacyl-tRNA enters the A site, a peptide bond forms between the amino acids, the ribosome translocates, and the now uncharged tRNA exits via the E site. This intricate dance is part of the vital process by which ribosomes create polypeptide chains, eventually folding into functional proteins that are essential for life.